Simple potentiometry and cyclic voltammetry techniques for sensing Hg2+ ions in water using a promising flower-shaped WS2-WO3/poly-2-aminobenzene-1-thiol nanocomposite thin film electrode

A highly promising flower-shaped WS2-WO3/poly-2-aminobenzene-1-thiol (P2ABT) nanocomposite was successfully synthesized via a reaction involving 2-aminobenzene-1-thiol, Na2WO4, and K2S2O8 as oxidants. The WS2-WO3/P2ABT nanocomposite demonstrated remarkable potential as a sensor for detecting harmful Hg2+ ions in aqueous solutions. The sensing behavior was evaluated over a wide concentration range, from 10−6 to 10−1 M, using a simple potentiometric study on a two-electrode cell. The calibration curve yielded an excellent Nernstian slope of 33.0 mV decade−1. To further validate the sensing capabilities, cyclic voltammetry was employed, and the results showed an increasing trend in the cyclic voltammetry curve as the Hg2+ concentration increased from 10−6 to 10−1 M with an evaluated sensitivity of 2.4 μA M−1. The WS2-WO3/P2ABT nanocomposite sensor exhibited exceptional selectivity for detecting Hg2+ ions, as no significant effects were observed from other interfering ions such as Zn2+, Ni2+, Ca2+, Mg2+, Al3+, and K+ ions in the cyclic voltammetry tests. Furthermore, the sensor was tested on a natural sample that was free of Hg2+ ions, and the cyclic voltammetry curves did not produce any characteristic peaks, confirming the sensor's specificity for Hg2+ detection. The sensor's cost-effectiveness and ease of fabrication present the potential for developing a simple and practical sensor for detecting highly poisonous ions in aqueous solutions.


Introduction
Some vital organic molecules depend on inorganic mineral ions for their vital roles; however, these minerals may show some toxicity and are present in the environment for long periods because they are vital, which makes them common pollutants in the world.As mentioned above, and due to their importance, it is necessary to monitor and determine the levels of heavy metals in the environment, water, soil, and air.Potentiometric electrochemical analysis techniques are indeed simple and promising methods used for various purposes, especially in elds such as analytical chemistry and electrochemistry.These techniques rely on the measurement of potential (voltage) between two electrodes, which can provide valuable information about the analyte of interest.Some common potentiometric techniques include pH measurements, ion-selective electrodes, and redox potential measurements. 1,2The permissible limit for most toxic heavy metals according to the Environmental Protection Agency is less than 10 parts per billion (10 ppb) in groundwater, while according to WHO, the limit of Hg 2+ ions is 1.0 ppm. 3 In the medical eld, identifying mercury or mercury dioxide is important for diagnosing mercury poisoning in patients.Mercury exposure, especially from sources such as contaminated sh or dental amalgams, can lead to severe health issues.Early detection of mercury levels in patients allows for timely intervention and appropriate treatment to mitigate the toxic effects. 4n environmental analysis, the detection and quantication of mercury in various matrices such as air, water, soil, and other environmental samples is crucial for evaluating pollution levels and understanding potential ecological risks.][7][8] Some studies based on the detection and quantication of heavy metals in biomedia through color analysis demand RSC Advances PAPER a combination of technical expertise, sophisticated equipment, and rigorous protocols to overcome the challenges posed by their low concentrations and potential sample contamination.Nevertheless, these efforts are essential to gain insights into the presence and levels of these metals in biomedia, contributing to a deeper understanding of their role in biological processes and potential health implications.These studies face challenges related to high costs and highly complex techniques.Several sophisticated and intricate analytical methods are employed, including atomic absorption spectroscopy (AAS), mass spectrometers, ame atomic absorption, X-ray uorescence (XRF), laser thermal lens spectroscopy, neutron activation analysis, plasma block associated with research, and optical emission spectroscopy of plasma.][11][12] An economical technique for detecting mercury or mercury dioxide is highly benecial as it promotes widespread accessibility and adoption, particularly in settings with limited resources.These cost-effective methods can nd applications in various sectors, including medical facilities, environmental monitoring agencies, research institutions, and community initiatives, enabling extensive monitoring, and management of mercury pollution.The use of affordable approaches for mercury identication contributes to the protection of public health, environmental preservation, and sustainable development by effectively addressing the risks associated with mercury exposure and contamination.
Herein, a ower-like WS 2 -WO 3 /P2ABT nanocomposite was effectively synthesized and employed as a sensor for detecting Hg 2+ ions that showed promising performance.The sensing capabilities of this nanocomposite sensor were evaluated using both two and three-electrode cells, employing simple and cyclic voltammetry systems.Calibration curves obtained from the simple potentiometric study conrmed the excellent sensitivity of the WS 2 -WO 3 /P2ABT sensor to Hg 2+ ions.The calibration curve demonstrates a clear and linear relationship between the potential response and the concentration of Hg 2+ ions, showcasing the sensor's ability to accurately detect varying Hg 2+ concentrations.
Similarly, the cyclic voltammetry curves further validated the sensor's sensitivity to Hg 2+ ions.The curves exhibited increasing responses as the Hg 2+ concentration increased, and the area under the cyclic curve that was typically located at 0.1 V increased accordingly.These ndings reinforced the nanocomposite sensor's effectiveness in detecting Hg 2+ ions with high sensitivity.Furthermore, the nanocomposite sensor exhibited remarkable selectivity for Hg 2+ ions, as observed in the cyclic voltammetry tests.Interfering ions, including other metal ions, are shown to have no effects on the sensor's sensitivity behavior.The absence of characteristic peaks in the cyclic voltammetry curves for interfering ions conrmed the sensor's ability to specically target and respond to Hg 2+ ions while avoiding false positive signals from other elements.The combination of simple and cyclic voltammetry techniques, along with the excellent sensitivity and selectivity demonstrated by the WS 2 -WO 3 /P2ABT nanocomposite sensor, highlights its potential for practical applications in Hg 2+ detection.The sensor's reliability, sensitivity, and selectivity open up possibilities for environmental monitoring, industrial analysis, and health-related applications, contributing to improved safety and environmental protection.The elemental composition was determined through XPS analyses conducted with equipment from Kratos Analytical in Manchester, UK.Crystalline characteristics were identied using XRD (X'Pert Pro) based in Almelo, The Netherlands.Furthermore, the FTIR analysis was performed using a Bruker device from Easton, USA.In addition, topographical and morphological features were observed using TEM (EOL JEM-2100) and SEM (ZEISS) based in Oberkochen, Germany.

Preparation of WS 2 -WO 3 /P2ABT nanocomposite
The process of oxidative polymerization plays a pivotal role in the creation of P2ABT.In this procedure, 0.06 M of the monomer 2ABT was dissolved in 1.0 M hydrochloric acid (HCl), and an oxidizing agent (0.14 M) was employed to transform the monomer into P2ABT by initiating the formation of free radicals, in which the total volume was 100 ml.This chemical reaction occurred at ambient room temperature and was continued for 24 h.Following the appropriate treatment, the resultant polymer was derived and prepared for utilization in subsequent applications.
The fabrication of the WS 2 -WO 3 /P2ABT nanocomposite thin lm involves the oxidation of 2ABT, accomplished by employing a mixture comprising 0.06 M (50 ml) of Na 2 WO 4 and 0.06 M of K 2 S 2 O 8 .By employing the combination of Na 2 WO 4 as an oxidizing agent in conjunction with K 2 S 2 O 8 , this process resulted in the integration of WO 3 and WS 2 into the polymer matrix, facilitating the formation of the composite.Additionally, the presence of Cl − ions leads to physically drawing the polymer network due to the utilization of HCl as the acid medium.This chemical reaction was allowed to proceed for a duration of 24 h to guarantee the successful creation of the desired nanocomposite thin lm.

The potentiometric sensing
The WS 2 -WO 3 /P2ABT nanocomposite was utilized as a potentiometric sensor for detecting Hg 2+ ions.The negative charge present on the nanocomposite enabled the physical attraction of Hg 2+ ions from the solution, and the concentration of Hg 2+ ions affected the calibration curve.For evaluating the sensing behavior, a two-electrode cell was employed with a simple potentiometric technique.The WS 2 -WO 3 /P2ABT nanocomposite served as the primary sensing electrode, and a calomel electrode (Hg/Hg 2 Cl 2 ) was used as the reference electrode.
To assess sensitivity and the inuence of interfering ions, the cyclic voltammetry technique was employed in a three-electrode cell conguration using CHI608E.The WS 2 -WO 3 /P2ABT nanocomposite served as the working sensing electrode, alongside the calomel electrode, and was accompanied by the counter electrode (which was a graphite electrode, 1.0 cm 2 ).Moreover, the performance of the sensing technique was validated by testing natural samples using the above-mentioned methodologies.This approach allowed researchers to assess the sensor's reliability and accuracy under real-world conditions and determine its applicability for environmental monitoring and practical applications.As such, the WS 2 -WO 3 /P2ABT nanocomposite demonstrated promising potential as a sensitive and selective potentiometric sensor for Hg 2+ ions, with its performance validated through both potentiometric and cyclic voltammetry techniques.The sensor's capability to effectively detect Hg 2+ ions, along with its assessment in natural samples, made it a valuable tool for environmental monitoring and detection of Hg 2+ contamination in various settings.

Analyses
The structural makeup of P2ABT and the WS 2 -WO 3 /P2ABT nanocomposite was examined by analyzing the positions of functional groups through FTIR analysis, as shown in Fig. 1(a).FTIR analysis allowed us to assess the positions of these functional groups by examining the vibration of bonded electrons.When the polymer matrix was lled with the inorganic material (WS 2 -WO 3 ), this lling effect inuenced the bond vibrations, leading to observable shis in the positions of these functional groups in the nanocomposite compared to those in the pure P2ABT polymer.These shis can be observed as small red or blue shis, indicating a slight displacement to the right or le, respectively.The summary of the positions of these functional groups can be found in Table 1.
XRD patterns of the pure P2ABT polymer and WS 2 -WO 3 /P2ABT nanocomposite are presented in Fig. 1(b).The XRD pattern of pure P2ABT exhibited a semi-crystalline behavior characterized by small, sharp peaks observed in the range of 22.9°to 29.7°.This semi-crystalline nature is advantageous for various applications.
Fig. 1 The structural composition of P2ABT and WS 2 -WO 3 /P2ABT nanocomposite through (a) FTIR and (b) XRD analyses.The elemental analysis of the synthesized WS 2 -WO 3 /P2ABT nanocomposite was conducted using XPS, as shown in Fig. 2. The survey scan in Fig. 2(a) conrmed the presence of the elements W, O, S, C, and N in the nanocomposite.The W 4f spectra in Fig. 2(b) revealed the W 4f 7/2 and W 4f 5/2 peaks at 35.2 and 37.6 eV, respectively, indicating the formation of WS 2 (ref.22) and WO 3 . 23he S 2p spectra (Fig. 2(d)), ranging from 163 to 169 eV, corresponds to various sulfur bonds formed with different elements such as S-C and S-W, further conrming the presence of WS 2 within the polymer matrix.O 1s spectra (Fig. 2(c)) are located at 530.5 and 532 eV, 24,25 which correspond to O-W bonds.C and N elements were detected at 286 and 402 eV, respectively, consistent with the elements present in the pure P2ABT polymer.
Fig. 3(a) depicts the morphological characteristics of P2ABT, which exhibits a distinctive cle spherical ball shape with varying particle sizes ranging from 100 nm to 1 mm.The presence of these larger particles is believed to be the result of a combination of smaller ones during the formation process.The porous structure observed in these particles adds further advantages as it facilitates the formation of composite materials through additional reactions.
Furthermore, the porous structure observed in these particles enhances their surface area and provides additional active sites for potential reactions.This porous characteristic plays a crucial role in facilitating the formation of composite materials when these particles interact with other components in the reaction medium.The increased surface area allows for more extensive interactions and effective incorporation of other materials, leading to the formation of the desired composite structures.
The presence of porous P2ABT particles with a cle spherical ball shape offers great potential for various applications, especially in composite material synthesis.The unique morphology and porous structure of P2ABT particles open up opportunities for tailored material design and innovative applications in elds such as catalysis, sensing, and energy storage, where composite materials play a signicant role.
In contrast, the prepared WS 2 -WO 3 /P2ABT nanocomposite exhibits a novel ower-shaped morphology composed of very small particles with sizes less than 100 nm.These tiny particles aggregate together, giving rise to distinctive and promising ower-shaped structures, as shown in Fig. 3(c and d).The ower-shaped morphology of the nanocomposite is particularly advantageous as it results in leaf-like structures, increasing the material's surface area.This enlarged surface area provides numerous active sites that signicantly contribute to the nanocomposite's excellent sensing behavior.The presence of these active sites on the large surface of the ower-shaped nanocomposite enables it to efficiently interact with the target analyte, facilitating highly sensitive and selective sensing.These active sites offer ample opportunities for chemical interactions and binding of the analyte molecules, making the nanocomposite a highly effective sensor.The ower-shaped morphology and the associated leaf-like structures offer unique features that distinguish the WS 2 -WO 3 /P2ABT nanocomposite from conventional materials.This morphology, along with the abundance of active sites, makes the nanocomposite highly promising for a range of sensing applications, including environmental monitoring, healthcare diagnostics, and industrial process control.The visual representation shown in Fig. 3(c and d) showcases the intricate and fascinating ower-shaped structure of the WS 2 -WO 3 /P2ABT nanocomposite, highlighting its potential for innovative sensing technologies.This remarkable morphology enhances the nanocomposite's performance and makes it a valuable candidate for various sensor applications with heightened sensitivity and selectivity.
The TEM image shown in Fig. 3(b) vividly illustrates the behavior of the WS 2 -WO 3 /P2ABT nanocomposite.In the image, the dark shapes correspond to the inorganic ller, while the gray color represents the polymer materials.The distinct contrast in the TEM image between the dark and gray regions is a clear indication of the segregation of the inorganic ller and the polymer components within the nanocomposite.This segregation is a characteristic feature of the well-dispersed nanocomposites, where the inorganic and polymer phases are spatially separated.
The dark shapes, representing the inorganic ller (WS 2 -WO 3 ), are interspersed within the gray polymer matrix (P2ABT).This arrangement indicates a successful synthesis of the nanocomposite, with the inorganic ller being uniformly distributed and embedded within the polymer matrix.
Such a well-dispersed conguration is crucial for optimizing the properties of nanocomposites and performance.The spatial separation of the inorganic and polymer phases ensures that each component retains its unique characteristics, thereby enhancing the overall behavior and functionality of the nanocomposite.The TEM image provides valuable visual evidence of the nanocomposite's structure, reaffirming the successful formation of the WS 2 -WO 3 /P2ABT nanocomposite with a well-dened interface between the inorganic and polymer components.This well-dispersed morphology is pivotal for harnessing the synergistic effects of both materials and realizing the nanocomposite's potential for various applications, including sensing, catalysis, and energy-related technologies.

Sensing properties
The sensing behavior of the WS 2 -WO 3 /P2ABT nanocomposite sensor for Hg 2+ detection is effectively demonstrated using the simple potentiometric method, as shown in Fig. 4.This sensing method holds great promise for detecting Hg 2+ ions, as the concentration of Hg 2+ directly correlates with the potential difference observed between the sensing electrode and the reference electrode.
As the concentration of Hg 2+ ions increases from 10 −4 to 10 −1 M, the potential difference also increases, ranging from 131 mV to 230 mV.The obtained Nernstian slope of 33.0 mV decade −1 indicates a highly promising linear relationship between the potential and the logarithm of Hg 2+ concentration.
The nanocomposite sensor exhibits an impressive detection limit of 9 × 10 −5 M, showcasing its sensitivity to low concentrations of Hg 2+ ions.This low detection limit underscores the sensor's capability to detect trace amounts of Hg 2+ in various sample matrices, which is crucial for environmental monitoring and health-related applications.
Furthermore, the nanocomposite sensor's low-cost and ecofriendly behavior makes it an attractive option for practical applications for Hg 2+ detection.The use of cost-effective and environmentally friendly materials is advantageous for promoting sustainable and accessible sensing technologies.
Overall, the promising linear behavior, high sensitivity, and cost-effective and eco-friendly nature of the WS 2 -WO 3 /P2ABT nanocomposite sensor make it a highly viable and valuable candidate for Hg 2+ detection, with potential applications in environmental monitoring and health sciences.
The detection of Hg 2+ ions over a concentration range from 10 −6 to 10 −1 M was carried out using the WS 2 -WO 3 /P2ABT thin lm sensor, employing the cyclic voltammetry technique, as demonstrated in Fig. 5(a).The results showed that the produced current density increases progressively as the Hg 2+ ion concentration rises from 10 −6 to 10 −1 M.This increasing trend is a clear reection of the high sensitivity of the WS 2 -WO 3 /P2ABT thin lm sensor towards Hg 2+ ions, where higher concentrations lead to a Fig. 4 A simple potentiometric method for the detection of Hg 2+ ions (10 −6 to 10 −1 M) using the WS 2 -WO 3 /P2ABT thin film sensor.As shown in Fig. 5(b), the sensitivity of the WS 2 -WO 3 /P2ABT thin lm sensor was quantied, and it was calculated to be 2.4 mA M −1 .This value indicated how effectively the sensor responded to the changes in the Hg 2+ ion concentration.A higher sensitivity value suggested that even small variations in Hg 2+ concentration can be accurately detected by the sensor.
The cyclic voltammetry technique, coupled with the WS 2 -WO 3 /P2ABT thin lm sensor, provided a powerful and sensitive means for detecting Hg 2+ ions across a wide concentration range.The excellent sensitivity and responsiveness of the sensor make it a valuable tool for environmental monitoring and various analytical applications, where precise detection of Hg 2+ ions is essential.
The combined results presented in Fig. 5(a-c) emphasize the capability of the WS 2 -WO 3 /P2ABT thin lm sensor in effectively detecting and quantifying Hg 2+ ions, making it a promising candidate for practical sensing applications, especially in the elds related to environmental protection and public health.The reproducibility of the WS 2 -WO 3 /P2ABT thin lm sensor to Hg 2+ ions is shown in Fig. 5(d), from this gure, the produced cyclic voltammetry is almost the same value with a very limited standard deviation value.From these data, the limit of detection (LOD) is 0.1 mg L −1 which is a promising value for the detection of Hg 2+ ions.
The accuracy of Hg 2+ ion recovery can be assessed by examining the current density values obtained from repeated measurements, as illustrated in Fig. 5(c).By conducting the measurements three times and analyzing the resulting current density, it provides a direct reection of the Hg 2+ ion concentration.As observed, the recovery values consistently indicated 96.8% across three consecutive measurement cycles.This suggested that the methodology yields a high degree of precision and consistency in estimating the concentration of Hg 2+ ions, reinforcing the reliability of the analytical approach for Hg 2+ ion recovery assessment.
The effectiveness and selectivity of the WS 2 -WO 3 /P2ABT thin lm sensor for Hg 2+ ions were conrmed through the testing of other interfering ions.A series of solutions containing interfering ions, including K + , Mg 2+ , Al 3+ , Ca 2+ , Zn 2+ , and Ni 2+ , at a concentration of 0.01 M, were prepared and subjected to the sensor using cyclic voltammetry, as depicted in Fig. 6(a).The results demonstrated that the WS 2 -WO 3 /P2ABT thin lm sensor exhibited no response to these interfering elements.No peaks or signicant changes in the current density were observed, indicating that these ions do not interfere with the sensing capabilities of the prepared sensor for Hg 2+ ions.
This lack of response to the interfering ions highlights the sensor's remarkable selectivity for Hg 2+ ions over other tested elements.The WS 2 -WO 3 /P2ABT thin lm sensor exhibited excellent specicity in detecting Hg 2+ ions even in the presence of potentially interfering ions commonly found in the environmental samples.
The absence of peaks or any signicant signal interference from the interfering ions conrmed the high accuracy and reliability of the WS 2 -WO 3 /P2ABT thin lm sensor for detecting Hg 2+ ions.Such selectivity is of paramount importance in practical applications, as it ensures the sensor's capability to precisely identify and quantify Hg 2+ ions in complex sample matrices.
Overall, the successful validation of the WS 2 -WO 3 /P2ABT thin lm sensor's selectivity against interfering ions in Fig. 6(a) further underscores its potential as a robust and accurate tool for Hg 2+ ion detection in various real-world scenarios, making it an essential asset for environmental monitoring and analytical chemistry applications.
The study of natural samples on the fabricated WS 2 -WO 3 /P2ABT thin lm sensor is presented in Fig. 6(b).The natural samples tested included tap water and underground water collected from Egypt, specically from the Beni-Suef city.Additionally, a laboratory-prepared Hg 2+ sample, equivalent to the natural samples, was included in the analysis.
The curves obtained from the testing showed that the tap water and underground water samples had no signicant effect on the WS 2 -WO 3 /P2ABT thin lm sensor.No peaks were observed in the curves, indicating that these natural samples did not interfere with the sensor's performance or generate any false signals.
In contrast, the Hg 2+ sample exhibited a distinct characteristic peak in the curve, conrming the sensor's sensitivity and selectivity for detecting Hg 2+ ions.The presence of the characteristic peak in the Hg 2+ sample curve validated the sensor's ability to accurately identify and quantify Hg 2+ ions even in complex natural sample matrices.The lack of peaks in the curves of tap water and underground water samples further conrmed the sensor's specicity and reliability in distinguishing Hg 2+ ions from other components in the natural samples.This level of selectivity is crucial in real-world applications where environmental samples can contain various contaminants and interfering substances.
To gain further insights into the electrical performance of the fabricated WS 2 -WO 3 /P2ABT nano-composite sensor, impedance measurements were conducted in the presence of 0.01 M Hg 2+ ions and an additional 0.01 M NaCl electrolyte.The resulting Nyquist plot shown in Fig. 7 reveals a distinct semicircular pattern, indicating a dened electrical response.The solution resistance (R s ) was determined to be 6.0 U, while the charge transfer resistance (R CT ) was measured at 27 U.These impedance values highlight the promising potential of the sensor for Hg 2+ ion detection, showcasing its ability to provide a reliable and efficient electrical response.This impedance analysis provided valuable information about the sensor's electrical characteristics, complementing the understanding gained from the J ph measurements and emphasizing its suitability for Hg 2+ estimation.
Overall, the results depicted in Fig. 6(b) demonstrate the excellent performance of the WS 2 -WO 3 /P2ABT thin lm sensor for Hg 2+ detection in natural samples, underscoring its potential as a robust and effective tool for environmental monitoring and water quality assessment.Its ability to accurately detect Hg 2+ ions amidst diverse natural sample matrices makes it a valuable asset in addressing environmental and health-related concerns associated with mercury contamination.
The rationale behind employing the WS 2 -WO 3 /P2ABT thin lm sensor for detecting Hg 2+ lies in the strong affinity of Hg 2+ ions for the inorganic WS 2 -WO 3 materials, forming anticipated partial coordination bonds.Furthermore, P2ABT serves a dual function by establishing physical electrostatic attraction bonds with this metal through both its N and S atoms.The interaction between Hg 2+ ions and the WS 2 -WO 3 /P2ABT thin lm sensor was characterized by charge attraction, resulting in a noticeable shi in the lm potential, as evidenced by the produced J ph value.In scenarios where the Hg 2+ concentration is substantial, there is a concurrent increase in the lm potential, leading to an elevation in the J ph value. 26Conversely, as the Hg 2+ concentration diminishes, the produced J ph value exhibits a corresponding decrease.This dynamic relationship underscores the sensitivity of the thin lm to Hg 2+ ions.The charge dynamics within the thin lm are instrumental in understanding the sensor's response to varying concentrations of Hg 2+ .The substantial increase in the lm potential under higher Hg 2+ concentrations signies a heightened affinity between the lm and the ions, resulting in an augmented J ph value. 21This behavior can be attributed to the electrostatic forces between the lm and the charged Hg 2+ ions, inuencing the charge carrier density and, consequently, the generated photocurrent. 27Additionally, this polymer plays a crucial protective role in safeguarding the sensor against corrosion, thereby enhancing its overall stability.Table 2 illustrates the great behavior of this fabricated sensor related to other previous literature.
The thermal gravimetric analyses of the synthesized WS 2 -WO 3 /P2ABT nanocomposite are depicted in Fig. 8.The TGA analysis is conducted in three phases: the initial stage at 133 °C revealed a mass loss of 5.9%, attributed to the removal of the physically adsorbed H 2 O molecules on the nanocomposite particles.The second stage, occurring at 215 °C, corresponds to the partial degradation of the polymer's sulfur component.The nal stage, at 357 °C, pertains to the decomposition of the polymer rings and the conversion of WS 2 into tungsten, accompanied by the degradation of sulfur atoms.This TGA prole exhibits promise for a sensor designed to operate at room temperature, as the cumulative mass loss up to 357 °C reaches 26.9%.

Fig. 5
Fig. 5 (a and b) WS 2 -WO 3 /P2ABT thin film sensor for Hg 2+ ions through the cyclic voltammetry, (c) the calculated sensitivity for Hg 2+ ions, and (d) the reproducibility of the sensor to Hg 2+ ions.

Fig. 6
Fig. 6 (a) WS 2 -WO 3 /P2ABT thin film sensor for Hg 2+ ions by testing the response of the (a) interfering ions at 0.01 M and (b) natural samples.

Table 1
The band assignments of P2ABT and WS 2 -WO 3 /P2ABT nanocomposites from the FTIR analyses